Anomalous Thermoelectric Behavior of BiSeTe Doped with SiGe:As

BiSeTe and BiSbTe have been two of the most efficient thermoelectric materials near room temperature applications for many years. In spite of recent progress in enhancement of the efficiency of BiSbTe thermoelectric materials, there has been little progress in developing efficient BiSeTe alloys. BiSeTe is an n-type thermoelectric material with negative Seebeck value and BiSbTe is p-type with positive Seebeck. We observed BiSeTe changes to p-type with the addition of 5% arsenic doped SiGe. After annealing process the Seebeck value changed sign again resulting in n-type BiSeTe. The electrical conductivity and thermal conductivity also changed during the course of annealing. Interestingly the minimum thermal conductivity corresponded to the maximum electrical conductivity and power factor of the p-type mode. This effect may prove to be a cornerstone in the enhancement and fabrication of thermoelectric devices based on bismuth telluride based alloys.